Murderers of police officers are to be given whole-life sentences and be left to die in prison, the home secretary, Theresa May, is to reveal at the Police Federation conference.

May says it is time for "life to mean life" in such cases because murdering a police officer in the course of their duty represents an attack on the "fundamental basis of our society".

She will tell the Police Federation on Wednesday: "We ask police officers to keep us safe by confronting and stopping violent criminals for us. We ask them to take risks so that we don't have to. That is why I am clear that life should mean life for anyone convicted of killing a police officer."

The move by May, who was jeered and heckled when she addressed the Police Federation conference last year, is likely to come into effect within months, and to receive a warm welcome from rank-and-file police officers. It will also thrill Tory backbenchers and seal May's reputation as a hardline Conservative home secretary trying to put some steel into the party.

Twelve police officers have been killed while on duty since 2000.

The latest to die were two women police officers, Nicola Hughes and Fiona Bone, who were killed during a gun and grenade attack when they responded to a routine burglary call last September in Manchester. Dale Creggan, aged 29, who has admitted murdering them, is yet to be sentenced as he is currently on trial for the separate killing of a father and son, which he denies.

Crown Prosecution Service guidelines currently reserve whole-life sentences for serial killers, child murderers or those who kill in the name of religion, politics or an idelogical cause.

The current starting point for the murder of a police or prison officer in the course of their duty is a life sentence with a minimum term of 30 years. David Bieber, who murdered PC Ian Broadhurst in December 2003, received a life sentence with a minimum of 37 years before he could be considered for parole.

Mustaf Jama, Yusuf Jama and Muzzaker Shah, the members of a criminal gang that shot dead PC Sharon Beshenivsky during a robbery in Bradford in 2005, were all given life sentences with a minimum term of 35 years.

The longest-serving police killer is Harry Roberts, who was imprisoned in 1966 for the murder of three police officers in Shepherd's Bush, in west London. He was sentenced to a minimum term of 30 years before he could apply for parole but he has so far served 46 years. The parole board last decided in 2009 that he remained a risk to the public after he made violent threats to the owners of an animal sanctuary where he was working on day release.

The whole-life sentence was introduced in 1983, when Michael Howard was home secretary. Since then, at least 63 murderers have been told they will not be released from jail, including 23 as a result of an executive decision. They include Ian Brady, Rosemary West and Harold Shipman.

The change is to be made by the justice secretary, Chris Grayling, who will make an order under the 2003 Criminal Justice Act to change the starting point for the murder of a police officer from 30 years to a whole-life order. Grayling is shortly to consult the sentencing council, which represents the judges, on the move.

May said earlier this week that she was looking forward to the conference: "It is always an interesting experience," she said.